1. Field of the Invention
The present invention relates to a circuit and method for recognizing an interruption in a light waveguide link between a transmission unit and at least one intensifying fiber wherein an amplified spontaneous emission generated by the fiber is detected.
2. Description of the Prior Art
In optical fiber transmission systems having great distances between a pump laser and a fiber which intensifies the light of the pump laser, the pump laser must emit extremely high luminous power so that the intensifying fiber still receives enough light for intensification. In case of an interruption which is caused, for example, by a break or a separation of the light waveguide link, laser light having high luminous power can emerge from a fiber that lead to health hazards for a person.
In order to avoid health hazards, a light waveguide link or a separate monitoring channel was hitherto additionally established along a light waveguide link so as to monitor a closed condition of the transmission path. These monitoring devices, however, are accompanied by the disadvantage that the circuit-oriented outlay for regeneration and evaluation of the light signals is very high given very long link lengths of a light waveguide connection.
An object of the present invention, therefore, is to specify a circuit arrangement and an appertaining method for monitoring a light waveguide connection.
Accordingly, the present invention provides both a method and circuit for recognizing an interruption of a light waveguide link between a transmission unit and at least one intensifying fiber wherein an amplified spontaneous emission generated by the fiber is detected.
The present invention yields the advantage that no separate monitoring channel need be established along a light waveguide link.
The invention yields the further advantage that arbitrarily long light waveguide links can be monitored with a minimal circuit-oriented outlay.
Another advantage of the present invention is that only the first transmission section of a light waveguide link need be monitored.
Yet another advantage of the present invention is that a fast shut-off of the optical transmitter ensues.
The present invention yields the further advantage that the monitoring unit is not dependent on devices such as, for example, receiver units, return transmission units or control units.
Moreover, the present invention yields the advantage that, given outage of a light waveguide, only the pump laser that supplies light into this light waveguide need be shut off. A transmission unit of a intact optical light waveguide connection in, for example, the opposite transmission direction remains in operation.
Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Preferred Embodiments and the Drawings.